OpenSSH 7.2 released

Posted on Posted in SSH

OpenSSH 7.2 has just been released. It will be available from the mirrors listed at http://www.openssh.com/ shortly.

OpenSSH is a 100% complete SSH protocol 2.0 implementation and includes sftp client and server support. OpenSSH also includes transitional support for the legacy SSH 1.3 and 1.5 protocols that may be enabled at compile-time.

Changes since OpenSSH 7.1p2: This is primarily a bugfix release.

Security:

  • ssh(1), sshd(8): remove unfinished and unused roaming code (was already forcibly disabled in OpenSSH 7.1p2).
  • ssh(1): eliminate fallback from untrusted X11 forwarding to trusted forwarding when the X server disables the SECURITY extension.
  • ssh(1), sshd(8): increase the minimum modulus size supported for diffie-hellman-group-exchange to 2048 bits.
  • sshd(8): pre-auth sandboxing is now enabled by default (previous releases enabled it for new installations via sshd_config).

New Features:

  • all: add support for RSA signatures using SHA-256/512 hash algorithms based on draft-rsa-dsa-sha2-256-03.txt and draft-ssh-ext-info-04.txt.
  • ssh(1): Add an AddKeysToAgent client option which can be set to 'yes', 'no', 'ask', or 'confirm', and defaults to 'no'. When enabled, a private key that is used during authentication will be added to ssh-agent if it is running (with confirmation enabled if set to 'confirm').
  • sshd(8): add a new authorized_keys option "restrict" that includes all current and future key restrictions (no-*-forwarding, etc.). Also add permissive versions of the existing restrictions, e.g. "no-pty" -> "pty". This simplifies the task of setting up restricted keys and ensures they are maximally-restricted, regardless of any permissions we might implement in the future.
  • ssh(1): add ssh_config CertificateFile option to explicitly list certificates. bz#2436
  • ssh-keygen(1): allow ssh-keygen to change the key comment for all supported formats.
  • ssh-keygen(1): allow fingerprinting from standard input, e.g. "ssh-keygen -lf -"
  • ssh-keygen(1): allow fingerprinting multiple public keys in a file, e.g. "ssh-keygen -lf ~/.ssh/authorized_keys" bz#1319
  • sshd(8): support "none" as an argument for sshd_config Foreground and ChrootDirectory. Useful inside Match blocks to override a global default. bz#2486
  • ssh-keygen(1): support multiple certificates (one per line) and reading from standard input (using "-f -") for "ssh-keygen -L"
  • ssh-keyscan(1): add "ssh-keyscan -c ..." flag to allow fetching certificates instead of plain keys.
  • ssh(1): better handle anchored FQDNs (e.g. 'cvs.openbsd.org.') in hostname canonicalisation - treat them as already canonical and remove the trailing '.' before matching ssh_config.

Bugfixes:

  • sftp(1): existing destination directories should not terminate recursive uploads (regression in openssh 6.8) bz#2528
  • ssh(1), sshd(8): correctly send back SSH2_MSG_UNIMPLEMENTED replies to unexpected messages during key exchange. bz#2949
  • ssh(1): refuse attempts to set ConnectionAttempts=0, which does not make sense and would cause ssh to print an uninitialised stack variable. bz#2500
  • ssh(1): fix errors when attempting to connect to scoped IPv6 addresses with hostname canonicalisation enabled.
  • sshd_config(5): list a couple more options usable in Match blocks. bz#2489
  • sshd(8): fix "PubkeyAcceptedKeyTypes +..." inside a Match block.
  • ssh(1): expand tilde characters in filenames passed to -i options before checking whether or not the identity file exists. Avoids confusion for cases where shell doesn't expand (e.g. "-i ~/file" vs. "-i~/file"). bz#2481
  • ssh(1): do not prepend "exec" to the shell command run by "Match exec" in a config file, which could cause some commands to fail in certain environments. bz#2471
  • ssh-keyscan(1): fix output for multiple hosts/addrs on one line when host hashing or a non standard port is in use bz#2479
  • sshd(8): skip "Could not chdir to home directory" message when ChrootDirectory is active. bz#2485
  • ssh(1): include PubkeyAcceptedKeyTypes in ssh -G config dump.
  • sshd(8): avoid changing TunnelForwarding device flags if they are already what is needed; makes it possible to use tun/tap networking as non-root user if device permissions and interface flags are pre-established
  • ssh(1), sshd(8): RekeyLimits could be exceeded by one packet. bz#2521
  • ssh(1): fix multiplexing master failure to notice client exit.
  • ssh(1), ssh-agent(1): avoid fatal() for PKCS11 tokens that present empty key IDs. bz#1773
  • sshd(8): avoid printf of NULL argument. bz#2535
  • ssh(1), sshd(8): allow RekeyLimits larger than 4GB. bz#2521
  • ssh-keygen(1): sshd(8): fix several bugs in (unused) KRL signature support.
  • ssh(1), sshd(8): fix connections with peers that use the key exchange guess feature of the protocol. bz#2515
  • sshd(8): include remote port number in log messages. bz#2503
  • ssh(1): don't try to load SSHv1 private key when compiled without SSHv1 support. bz#2505
  • ssh-agent(1), ssh(1): fix incorrect error messages during key loading and signing errors. bz#2507
  • ssh-keygen(1): don't leave empty temporary files when performing known_hosts file edits when known_hosts doesn't exist.
  • sshd(8): correct packet format for tcpip-forward replies for requests that don't allocate a port bz#2509
  • ssh(1), sshd(8): fix possible hang on closed output. bz#2469
  • ssh(1): expand %i in ControlPath to UID. bz#2449
  • ssh(1), sshd(8): fix return type of openssh_RSA_verify. bz#2460
  • ssh(1), sshd(8): fix some option parsing memory leaks. bz#2182
  • ssh(1): add a some debug output before DNS resolution; it's a place where ssh could previously silently stall in cases of unresponsive DNS servers. bz#2433
  • ssh(1): remove spurious newline in visual hostkey. bz#2686
  • ssh(1): fix printing (ssh -G ...) of HostKeyAlgorithms=+...
  • ssh(1): fix expansion of HostkeyAlgorithms=+...

Documentation:

  • ssh_config(5), sshd_config(5): update default algorithm lists to match current reality. bz#2527
  • ssh(1): mention -Q key-plain and -Q key-cert query options. bz#2455
  • sshd_config(8): more clearly describe what AuthorizedKeysFile=none does.
  • ssh_config(5): better document ExitOnForwardFailure. bz#2444
  • sshd(5): mention internal DH-GEX fallback groups in manual. bz#2302
  • sshd_config(5): better description for MaxSessions option. bz#2531

Portability:

  • ssh(1), sftp-server(8), ssh-agent(1), sshd(8): Support Illumos/ Solaris fine-grained privileges. Including a pre-auth privsep sandbox and several pledge() emulations. bz#2511
  • Renovate redhat/openssh.spec, removing deprecated options and syntax.
  • configure: allow --without-ssl-engine with --without-openssl
  • sshd(8): fix multiple authentication using S/Key. bz#2502
  • sshd(8): read back from libcrypto RAND_* before dropping privileges. Avoids sandboxing violations with BoringSSL.
  • Fix name collision with system-provided glob(3) functions. bz#2463
  • Adapt Makefile to use ssh-keygen -A when generating host keys. bz#2459
  • configure: correct default value for --with-ssh1 bz#2457
  • configure: better detection of _res symbol bz#2259
  • support getrandom() syscall on Linux

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